1. Field of the Invention
The present invention relates to a sheet conveying device used in a document feeder of an image reader or an image forming apparatus, or used in a sheet post-processing unit (finisher) of an image forming apparatus, to an image reader having the sheet conveying device, and to an image forming apparatus, such as a copying machine, a printer, a facsimile, or a multifunctional product (MFP) including these functions, having the sheet conveying device or the image reader.
2. Description of the Related Art
In a sheet conveying device used in a document feeder and the like, as a technique using a feeler as a detecting member for detecting a sheet, the conventional technology disclosed in Japanese Patent Application Laid-open No. 2007-91402 is known, for example.
FIG. 8 is a schematic of an original setting unit included in an example of such a document feeder. In the configuration illustrated in FIG. 8, a cover 50, also functioning as a guide member for feeding an original, is closed in the direction of an arrow A while an original 1 is present in the original setting unit. A feeler 51 is a detecting member for detecting the presence of an original, and a sensor not illustrated is turned on or off in association with the operation of the feeler 51. A holder holding a rotation fulcrum 51a of the feeler 51 is disposed in the cover 50, and moves in association with an opening or a closing operation of the cover 50.
Because such a sheet detecting technique is generally well known, a detailed explanation thereof is omitted herein.
The conventional example illustrated in FIG. 8 has the following disadvantages.
When the original 1 is to be set, the cover 50 is usually closed. Even when the operation stops due to an erroneous feeding of the original 1 being conveyed, the cover 50 is once opened to remove the original 1, and the cover 50 is closed before setting the original 1 again. Therefore, such an operation will not result in the configuration illustrated in FIG. 8. However, if a normal operation is not performed, in other words, the cover 50 is closed after opening the cover 50 without removing the original 1, the original 1 might get damaged when the feeler 51 is brought in contact with the original 1, depending on an angle θ1 formed between the feeler 51 and the original 1.
In other words, when the angle θ1 is larger than 45 degrees, the possibility of the original 1 being damaged will increase; and when the angle θ1 is smaller, the damage on the original 1 is reduced.
Moreover, although the angle θ1 can be reduced by disposing the fulcrum 51a of the feeler 51 at a more upstream position as illustrated in FIG. 9, the fulcrum 51a cannot be always disposed at a more upstream position depending on the arrangement of the other components. Furthermore, the size of the device itself is increased, disadvantageously.
The present invention is made in consideration of such circumstances, and an object of the present invention is to provide a sheet conveying device that can remove such inconvenience of the conventional technique, and that can prevent a detecting member that detects the presence of a sheet from damaging the sheet. Another object of the present invention is to provide an image reader having such a sheet conveying device, and to provide an image forming apparatus having such a sheet conveying device or such an image reader.